In various machines, especially mobile agricultural machines, it may be desired to actuate certain drive apparatus in response to the position of a moveable member. For example, on agricultural machines such as drills, planters, etc., the machine earth working tools are carried by a frame which is typically moved between a lowered, working position and an elevated, transport position. The drive apparatus for operating the related seeding or planting mechanisms is typically engaged when the working tool frame is in the working position and is disengaged when the working tool is in the elevated transport position.
Typically, an electric magnetic clutch is used for operating the drive apparatus for the seeding or planting mechanisms, and the electric magnetic clutch is actuated by means of an electric switch in response to the position of the working tool frame relative to the position of the working tool frame wheels.
Conventionally, actuation of the seeding or planting mechanism drive apparatus occurs at one end-point position of the working tool frame relative to the wheels. That is, when the working tool frame has been moved to the fully lowered, ground-engaging position, the drive apparatus for the seeding or planting mechanism is actuated. Conversely, the drive apparatus for the seeding or planting mechanism is switched off when the working tool frame has been fully elevated to the road transport position.
The above-described conventional practice has certain disadvantages. For example, it may sometimes be desirable to initiate the drive apparatus for the seeding or planting mechanisms as the working tools are lowered, rather than waiting until the working tools reach the fully lowered, ground-engaging position.
Further, in some instances with conventional machines, the working tools, for one reason or another, may not be elevated to the fully raised, road transport position. Thus, the switch for turning off the the seeding or planting mechanism drive apparatus may not be automatically actuated. Accordingly, it would be desirable to provide means for actuating the switch to turn off the drive apparatus as the working tools begin to be elevated away from the ground-engaging position rather than waiting for the working tools to be raised to the fully elevated position.
It would also be desirable to provide a switch actuating assembly which could be located high enough above the ground so that it does not get fouled with debris. Also, it would be beneficial if such a switch actuating mechanism was substantially resistant to normal vibrations when the machine is being operated with the working tools in the lowered, ground-engaging position or with the working tools elevated in the road transport position. Finally, it would be desirable to provide an imroved actuating assembly which would prevent impact damage to the switch in response to movement of the actuating assembly components to or beyond the switch actuation point.